Locknut

ABSTRACT

A locknut having a polygonal body portion with a frustoconical crown extension at one end. A plurality of indentations are provided in selected flat surfaces of the body portion to form a corresponding number of locking regions in the bore of the nut. Each indentation is curved so that the ends of the indentation are deeper than the crest. As a result, the locking regions also are curved but flatter than the initial curvature of the bore, whereby added contact is provided between the locking regions and a mating male member.

I United States Patent [151 3,678,978

Davis et al. 51 July 25, 1972 [54] LOCKNUT Primary Examiner-Ramon S.Britts [72] inventors: James R. Davis, Bloomfield l-lllls; Arthur B.Blum, Utica, both of Mich, ma-Stanley Belsky [73] Assignee: StandardPreset! Steel Co., Jenkintown, [57] ABSTRACT A locknut having apolygonal body ponion with a frustoconi- [22] Filed: March 10, 1970 calcrown extension at one end. A plurality of indentations are provided inselected flat surfaces of the body portion to form a [211 App! l7045corresponding number of locking regions in the bore of the n mApplicaflon Data nut. Each indentation is curved so that the ends of theindentation are deeper than the crest. As a result, the locking regionsComlnuatlon 0f 765,876, 8, 1968- also are curved but flatter than theinitial curvature of the bore, whereby added contact is provided betweenthe locking US. regions and a mating male member 51 Int. Cl ..Fl6b 39/12[58] Field of Search ..l5 l/2l B, 21 A; 10/86 A, 86 10 Claims, 2 DrawingFigures Patented July 25, 1972 3,678,978

F/GZ

221 32 ,2?) ZZa ZZZ 'VENTORS JAM R. DAVIS ARTHUR B. BLUM ZAMOY ATTOR YLOCKNUT This application is a continuation of application Ser. No.765,876, filed Oct. 8, 1968, which application has now been abandoned.

The present invention relates, in general, to locknuts and, inparticular, to nuts in which the thread is deformed over selectedregions, whereby a nut and a mating bolt are held together in tightlyfitted engagement.

Various locknuts are available at the present time in which the lockingcharacteristic is derived by deforming or indenting the externalsurfaces of the nuts to develop deformed or distorted regions within thethreaded bores of the nuts. The deformations are such' that as thelocknut engages a mating bolt, the nut is stressed elastically and gripsthe bolt tightly.

For the most part, locknuts of this type which are available at thepresent time fail to satisfy concurrently the requirements ofsufficient, uniform and controllable locking action,

retention of the desired locking characteristic after a number ofapplications and removals, simplicity of design, ease of manufacture andreasonable cost.

Accordingly, it is an object of the present invention to provide a newand improved locknut.

It is another object of the present invention to provide a locknut whichderives its locking characteristic by being deformed at its surface andwhich overcomes the limitations and shortcomings of presently available,comparable devices. These objects, as well as others, are achieved inaccordance with a preferred embodiment of the present invention byproviding a locknut having a polygonal body portion and frustoconicalcrown portion at one end of the body portion. The body portion has aplurality of indentations in selected flat surfaces thereof which form acorresponding number of locking regions in the threaded bore of the nut.The indentations intersect the body portion and the frusto-conical crownportion whereby each indentation is located partially within the bodyportion and partially within the frustoconical crown portion. Thelocking regions extend in a direction substantially perpendicular to theaxis of the locknut and the mag nitude of the indentations is such thatthe locking regions cause the locknut to be stressed elastically whenthe locknut threadably engages a mating threaded member. Eachindentation includes an arcuate inner wall having a direction ofcurvature such that the ends of the arcuate wall are indented furtherthan the crest. By shaping the indentations in this manner, the lockingregions also remain curved, except these curves are flatter than theinitial curvature of the bore of the nut. As a result, added contact isprovided between the curved locking regions and a mating threadedmember, whereby an improved locking characteristic is derived.

For a better understanding of the present invention, together with otherand further objects thereof, reference is made to the followingdescription, taken in connection with the accompanying drawing, and itsscope will be pointed out in the appended claims.

Referring to the drawing:

FIG. 1 is a perspective view of a locknut constructed in accordance withthe present invention; and

FIG. 2 is a sectional view, on an enlarged scale, taken along line 2-2of FIG. 1.

As shown in FIG. 1, a locknut l0, constructed in accordance with thepresent invention, includes a polygonal body portion 12 and afrustoconical crown portion 14. For the embodiment of the inventionillustrated, the external surface of body portion 14 is hexagonal. Athreaded bore 16 extends axially of nut between upper end face 18 ofcrown portion 14 and lower end face 20 of body portion 12.

Locknut 10 is provided with a plurality of indentations 22 in selectedflat surfaces 12a of body portion 12. For the embodiment of theinvention illustrated, three indentations 22 are provided on alternateflat surfaces 120. lndentations 22 preferably are located in the flatsurfaces 12a at the juncture of body portion 12 and crown portion 14 sothat each indentation in the body portion extends slightly into thecrown portron.

As is clearly illustrated in FIG. 2, each indentation is defined by anarcuate vertical inner wall 22a, a pair of vertical sidewalls 22b, and ahorizontal base surface 22c. Each arcuate inner wall 22a is a portion ofa vertical cylinder having an axis which extends parallel to the axis ofnut 10. The direction of curvature of each arcuate inner wall 22a issuch that its cylinder either surrounds or intersects the threaded bore16 of the locknut. As a result, the maximum depth of each indentation 22occurs at the ends of the arcuate wall 220 and along the lines ofjuncture of the arcuate wall and vertical sidewalls 2212, while theminimum depth of each indentation exists near the middle of theindentation at the crest 22d of the arcuate v inner wall. For thepreferred embodiment of the invention being described, the height ofeach indentation 22 may be from 15 percent to 45 percent of the heightof flat surfaces 12a with the height of these flat surfaces beingdefined as the distance from lower end face 20 of the nut to themidpoint of curved line 12b extending between the upper corners of flatsurfaces 12a. The width of each indentation may be from 50 percent to 75percent of the width of its associated flat surface 12a.

As indentations 22 are formed, a corresponding number of distortedlocking regions 24 are formed in threaded bore 16. Locking regions 24are in radial and axial alignment with indentations 22. It is seen fromFIG. 2, that locking regions 24 are curved in generally the samedirection as the direction of curvature of arcuate walls 22a and extendbetween relatively undistorted regions 25 of the threaded bore. Thecurvature of the locking regions is achieved by the curved configurationof indentations 22. The radius of curvature of locking regions 24 isgreater than the radius of curvature of regions 25 of the threaded boreand the radius of the threaded bore prior to being distorted. As aresult, the threaded bore 16 assumes what may be termed a tri-roundularconfiguration. The magnitude of indentations 22 is such that lockingregions 24 cause locknut 10 to be stressed elastically as the locknutengages a mating bolt.

By developing curved locking regions, greater contact area is providedbetween the nut and a mating bolt than what may be achieved with a flator oppositely curved indentation. The curved locking regions cause thedistorted nut threads to conform more closely to the bolt threads,whereas a flat or oppositely curved indentation limits the contact areato a narrower region. Because of the greater contact area, the lockingforce is distributed more broadly to result in lower unit pressure inthe contact area. This, in turn, reduces the wear inherent in repeatedinstallations and removals of the nut onto and from the mating bolt andalso reduces the tendency toward galling. As a result, the curvedlocking regions create an improved locking characteristic.

lndentations 22 are formed by correspondingly shaped tools (not shown).To achieve the desired result, the tools are moved inward radially tocause a corresponding radially inward deformation of the threaded boreat the selected locations. By having the indentations extend inwardly ina direction substantially perpendicular to the axis of the locknut sothat there is little, if any, distortion of the threads in an axialdirection, optimum prevailing torque retention is achieved.

The radius of curvature of arcuate inner walls 22a may vary from oneapplication to another. It has been found, that the radius of thearcuate walls may be either less than or greater than the radius of animaginary circle centered on the axis of the nut and tangent to the flatsurfaces 12a. The range of the radius of arcuate walls 220 may extendfrom one-half to twice the radius of this imaginary circle.

The angle of vertical sidewalls 22b is selected to facilitate removal ofthe forming tool after completion of formation of the indentations. Forthe embodiment of the invention illus trated, vertical sidewalls 22b ofeach indentation are disposed an angle of 45 to the radius which bisectsthe arcuate segment. However, a considerably smaller angle, for example,10, may be used.

While there has been described what is at present considered to be thepreferred embodiment of this invention, it

will be obvious to those skilled in the art that various changes andmodifications may be made therein without departing from the inventionand it is, therefore, aimed to cover all such changes and modificationsas fall within the true spirit and scope of the invention.

What is claimed is:

l. A locknut having a body portion of polygonal external cross-sectionand a frusto-conical extension at one end of said body portion, saidlocknut also having a threaded bore extending throughout the axialextent thereof, said body portion having a plurality of radialindentations in selected flat surfaces thereof spaced from the cornersof said polygonal external cross-section, and said threaded bore havinga plurality of distorted locking regions in radial and axial alignmentwith said indentations and extending between relatively undistortedregions of said threaded bore, said indentations intersecting said bodyportion and said frustoconical extension whereby each of saidindentations is located partially within said body portion and partiallywithin said frusto-conical extension, said indentations being of a widthand of a height less than those of said flat surfaces, the magnitude ofsaid indentations being such that the locking regions cause said locknutto be stressed elastically when said locknut engages a mating threadedmember, each indentation having an arcuate inner wall which is part of acylinder that either surrounds or intersects said threaded bore and eachlocking region being curved in generally the same direction as thedirection of curvature of said undistorted region, said inner wall beingsubstantially parallel to the axis of said locknut throughout its axialextent, the radius of curvature of said locking regions being greaterthan the radius of curvature of said undistorted regions.

2. A locknut according to claim 1 wherein said arcuate inner wallsextend parallel to the axis of said locknut.

3. A locknut according to claim 1 wherein:

a. said external cross-section of said body portion is hexagonal andsaid body portion has three indentations in alternate flat surfacesthereof at the juncture of said body portion and said frusto-conicalsection;

b. each of said indentations extends across 50 percent to 70 percent ofthe width of the flat surface in which it is located; and

c. each of said indentations extends along percent to 45 percent of theheight of said body portion of said locknut.

4. A locknut having a body portion of polygonal external cross-sectionand a frusto-conical crown portion at one end of said body portion, saidlocknut also having a threaded bore extending axially thereof betweenthe top end of said crown portion and a second end of said body portion,said body portion having a plurality of indentations in selected flatsurfaces thereof spaced from the corners of said polygonal externalcross-section, and said threaded bore having a corresponding number ofdistorted locking regions in radial alignment with said indentations andextending between relatively undistorted regions in said threaded bore,said indentations intersecting said body portion and said crown portionwhereby each of said indentations is located partially within said bodyportion and partially within said crown portion, said indentations beingof a width and of a height less than those of said flat surfaces, saidlocking regions extending radially inward of said undistorted regionsand substantially perpendicular to the axis of said locknut, themagnitude of said indentations being such that the locking regions causesaid locknut to be stressed elastically when said locknut threadablyengages a mating threaded member, each of said indentations having aconvexly curved inner wall with ends indented further from theassociated flat surface than is the crest of said curved inner wall,said inner wall being substantially parallel to said axis throughout itsaxial extent and said locking regions being curved in generally the samedirection as the direction of ourof curvature of said undistortedregions.

5. A locknut according to claim 4 wherein said external cross-section ofsaid body portion is hexagonal and said body portion has threeindentations in alternate flat surfaces thereof.

6. A locknut according to claim 4 wherein the curvature of said innerwalls of said indentations is more flat than the curvature of saidthreaded bore prior to being distorted.

7. A locknut according to claim 5 wherein each of said indentationsextends across 50 percent to percent of the width of the flat surface inwhich it is located.

8. A locknut according to claim 7 wherein each of said indentationsextends along 15 percent to 45 percent of the height of said bodyportion of said locknut.

9. A locknut having a'body portion of polygonal external cross-sectionand a frustoconical extension at one end of said body portion, saidlocknut also having a threaded bore extending throughout the axialextent thereof,'said body portion having a plurality of radialindentations in selected flat surfaces thereof spaced from the cornersof said polygonal external cross-section, and said threaded bore havinga plurality of distorted locking regions in radial and axial alignmentwith said indentations and extending between relatively undistortedregions of said threaded bore, said indentations intersecting said bodyportion and said frustoconical extension whereby each of saidindentations is located partially within said body portion and partiallywithin said frustoconical extension, said indentations being of a widthand of a height less than those of said flat surfaces, the magnitude ofsaid indentations being such that the locking regions cause said locknutto be stressed elastically when said locknut engages a mating threadedmember, each indentation having an arcuate inner wall which is part of acylinder that either surrounds or intersects said threaded bore and eachlocking region being curved in generally the same direction as thedirection of curvature of said undistorted regions, the radius ofcurvature of said locking regions being greater than the radius ofcurvature of said undistorted regions.

10. A locknut having a body portion of polygonal external cross-sectionand a frustoconical crown portion at one end of said body portion, saidlocknut also having a threaded bore extending axially thereof betweenthe top end of said crown portion and a second end of said body portion,said body portion having a plurality of indentations in selected flatsurfaces thereof spaced from the corners of said polygonal externalcross-section, and said threaded bore having a corresponding number ofdistorted locking regions in radial alignment with said indentations andextending between relatively undistorted regions in said threaded bore,said indentations intersecting said body portion and said crown portionwhereby each of said indentations is located partially within said bodyportion and partially within said crown portion, said indentations beingof a width and of a height less than those of said flat surfaces, saidlocking regions extending radially inward of said undistorted regionsand substantially perpendicular to the axis of said locknut, themagnitude of said indentations being such that the locking regions causesaid locknut to be stressed elastically when said locknut threadablyengages a mating threaded member, each of said indentations having aconvexly curved inner wall with ends indented further from theassociated flat surface than is the crest of said curved inner wall, andsaid locking regions being curved in generally the same direction as thedirection of curvature of said inner walls of said indentations, theradius of curvature of said locking regions being greater than theradius of curvature of said undistorted regions,

1. A locknut having a body portion of polygonal external crosssectionand a frusto-conical extension at one end of said body portion, saidlocknut also having a threaded bore extending throughout the axialextent thereof, said body portion having a plurality of radialindentations in selected flat surfaces thereof spaced from the cornersof said polygonal external crosssection, and said threaded bore having aplurality of distorted locking regions in radial and axial alignmentwith said indentations and extending between relatively undistortedregions of said threaded bore, said indentations intersecting said bodyportion and said frustoconical extension whereby each of saidindentations is located partially within said body portion and partiallywithin said frusto-conical extension, said indentations being of a widthand of a height less than those of said flat surfaces, the magnitude ofsaid indentations being such that the locking regions cause said locknutto be stressed elastically when said locknut engages a mating threadedmember, each indentation having an arcuate inner wall which is part of acylinder that either surrounds or intersects said threaded bore and eachlocking region being curved in generally the same direction as thedirection of curvature of said undistorted region, said inner wall beingsubstantially parallel to the axis of said locknut throughout its axialextent, the radius of curvature of said locking regions being greaterthan the radius of curvature of said undistorted regions.
 2. A locknutaccording to claim 1 wherein said arcuate inner walls extend parallel tothe axis of said locknut.
 3. A locknut according to claim 1 wherein: a.said external cross-section of said body portion is hexagonal and saidbody portion has three indentations in alternate flat surfaces thereofat the juncture of said body portion and said frusto-conical section; b.each of said indentations extends across 50 percent to 70 percent of thewidth of the flat surface in which it is located; and c. each of saidindentations extends along 15 percent to 45 percent of the height ofsaid body portion of said locknut.
 4. A locknut having a body portion ofpolygonal external cross-section and a frusto-conical crown portion atone end of said body portion, said locknut also having a threaded boreextending axially thereof between the top end of said crown portion anda second end of said body portion, said body portion having a pluralityof indentations in selected flat surfaces thereof spaced from thecorners of said polygonal external cross-section, and said threaded borehaving a corresponding number of distorted locking regions in radialalignment with said indentations and extending between relativelyundistorted regions in said threaded bore, said indentationsintersecting said body portion and said crown portion whereby each ofsaid indentations is located partially within said body portion andpartially within said crown portion, said indentations being of a widthand of a height less than those of said flat surfaces, said lockingregions extending radially inward of said undistorted regions andsubstantially perpendicular to the axis of said locknut, the magnitudeof said indentations being such that the locking regions cause saidlocknut to be stressed elastically when said locknut threadably engagesa mating threaded member, each of said indentations having a convexlycurved inner wall with ends indented further from the associated flatsurface than is the crest of said curved inner wall, said inner wallbeing substantially parallel to said axis throughout its axial extentand said locking regions being curved in generally the same direction asthe direction of curvature of said inner walls of said indentations, theradius of curvature of said locking regions being greater than theradius of curvature of said undistorted regions.
 5. A locknut accordingto claim 4 wherein said external cross-section of said body portion ishexagonal and said body portion has three indentations in alternate flatsurfaces thereof.
 6. A locknut according to claim 4 wherein thecurvature of said inner walls of said indentations is more flat than thecurvature of said threaded bore prior to being distorted.
 7. A locknutaccording to claim 5 wherein each of said indentations extends across 50percent to 70 percent of the width of the flat surface in which it islocated.
 8. A locknut according to claim 7 wherein each of saidindentations extends along 15 percent to 45 percent of the height ofsaid body portion of said locknut.
 9. A locknut having a body portion ofpolygonal external cross-section and a frustoconical extension at oneend of said body portion, said locknut also having a threaded boreextending throughout the axial extent thereof, said body portion havinga plurality of radial indentations in selected flat surfaces thereofspaced from the corners of said polygonal external cross-section, andsaid threaded bore having a plurality of distorted locking regions inradial and axial alignment with said indentations and extending betweenrelatively undistorted regions of said threaded bore, said indentationsintersecting said body portion and said frustoconical extension wherebyeach of said indentations is located partially within said body portionand partially within said frustoconical extension, said indentationsbeing of a width and of a height less than those of said flat surfaces,the magnitude of said indentations being such that the locking regionscause said locknut to be stressed elastically when said locknut engagesa mating threaded member, each indentation having an arcuate inner wallwhich is part of a cylinder that either surrounds or intersects saidthreaded bore and each locking region being curved in generally the samedirection as the direction of curvature of said undistorted regions, theradius of curvature of said locking regions being greater than theradius of curvature of said undistorted regions.
 10. A locknut having abody portion of polygonal external cross-secTion and a frustoconicalcrown portion at one end of said body portion, said locknut also havinga threaded bore extending axially thereof between the top end of saidcrown portion and a second end of said body portion, said body portionhaving a plurality of indentations in selected flat surfaces thereofspaced from the corners of said polygonal external cross-section, andsaid threaded bore having a corresponding number of distorted lockingregions in radial alignment with said indentations and extending betweenrelatively undistorted regions in said threaded bore, said indentationsintersecting said body portion and said crown portion whereby each ofsaid indentations is located partially within said body portion andpartially within said crown portion, said indentations being of a widthand of a height less than those of said flat surfaces, said lockingregions extending radially inward of said undistorted regions andsubstantially perpendicular to the axis of said locknut, the magnitudeof said indentations being such that the locking regions cause saidlocknut to be stressed elastically when said locknut threadably engagesa mating threaded member, each of said indentations having a convexlycurved inner wall with ends indented further from the associated flatsurface than is the crest of said curved inner wall, and said lockingregions being curved in generally the same direction as the direction ofcurvature of said inner walls of said indentations, the radius ofcurvature of said locking regions being greater than the radius ofcurvature of said undistorted regions.